The tan, where does that tan come from so sought after by some and so dreaded by others? The skin reacts appropriately to the sun. Under the effect of radiation, pigmentary substances, melanins, are produced which will absorb light and thus protect the cell from photo-oxidation. It will still take 48 to 72 hours after exposure to obtain a tan under the effect of UV rays. However, the ability of each of us to tan depends on his melanin capital (his skin color) and is totally under genetic control, no less than 25 genes compete for its formation!
UVB, few in number, but more nasty ...
There are actually 3 kinds of UV: UVA, UVB and UVC. You have never heard of it, this is normal because it does not cross the ozone layer!
UVA rays represent 95% to 98% of UV rays received, are very little tanning and do not burn. They darken the skin for a limited time and have no real effect on melanin synthesis knowing that it is useful for additional sunshine.
UVB represent 2 to 5% of UV rays received. They tan, burn the skin. UVB rays are known to damage DNA and can mutate a gene. The amount of UVB increases by about 4% when climbing 300m. The reflection of solar radiation is only 3% on grass, 5% on water, but 20% on sand! So on the beach, the reflection of the ground adds to the atmospheric diffusion even under the parasol.
Although they work differently, they both speed up aging of the skin. Sun protection is essential and the maximum protection index is SPF 50+. The terms "Full Screen" or "Full Protection" should no longer be used, as no product offers full protection against UV radiation. They all protect against UVB rays. Those which protect against UVA also bear the mention UVA in a circle.
The minimum for UV protection
Sun protection products prevent the action of UV rays by absorbing energy or by diffraction of light through a physical screen. Choose the highest protection index, especially for the face and neck. You get it, it won't stop you from tanning! it’s also the best time to put on hats if you like it!
Also note that antioxidant substances, such as carotenoids and vitamin E, can act to reduce oxidative stress at the cellular level. Carotenoids act by absorbing light at the level of the cell membrane. They are not synthesized by our body, they come from plants like dates, carrots, tomatoes, peppers, etc. It's up to you to enjoy it.
Self-tanners do not protect against the effects of the sun and worse, in some cases they can "manufacture" blackheads in an abusive manner.
Of course, sun exposure causes damage (photoaging, cancer, phototoxicity, etc.) but the sun also has excellent benefits: vitamin D synthesizer, energy supplier, antidepressant, mood regulator, etc. So do not fall into the opposite excess, the key is knowing how to protect yourself from it and use it wisely!